waiting for log buffer??
I don't understand what is happening (not unusual) in a particular
informix instance.
ids 7.30.UC7, hpux 10.20
a data loading script is building an index on a temporary table; there
are two temp dbspaces, the temp table was created 'with nolog', and
the build is using multiple threads.
at some point, other sessions, doing inserts and updates to unrelated
tables, get a 'G' in the onstat -u first flag position; at this time,
the index build session seems to be stuck in a critical section - it
shows a 'X' in flag four for a period of time (minutes, not seconds)
and the server is *not* in a ckp wait state
The sessions stuck on 'G', waiting for a log buffer, do nothing until
the index build completes, then continue merrily.
The log buffers are 32k default. The instance is logging to /dev/nul.
There are 8 log files of 500 MB each.
KAIO is being used, 4 cpuvps
If anyone could enlighten me as to what is happening, I would
appreciate it. A cure would be warmly received as well.
tia
James
Is your database in unbuffered or buffered logging mode ?
If you write your logfiles to /dev/null, you might also
considering using buffered logging (if not already done).
Then you might also increase the size of the log buffers,
32 KB is not too much (but enough if you use unbuffered logging).
Best regards
Eric
--
IT-Consulting Herber
Email: <mailto:eric@herber-consulting.de>
Mobile: +49 177 2276895
***********************************************
Download the IFMX Database-Monitor for free at:
http://www.herber-consulting.de/BusyBee
***********************************************
james wrote:
> I don't understand what is happening (not unusual) in a particular
> informix instance.
>
> ids 7.30.UC7, hpux 10.20
>
> a data loading script is building an index on a temporary table; there
> are two temp dbspaces, the temp table was created 'with nolog', and
> the build is using multiple threads.
>
> at some point, other sessions, doing inserts and updates to unrelated
> tables, get a 'G' in the onstat -u first flag position; at this time,
> the index build session seems to be stuck in a critical section - it
> shows a 'X' in flag four for a period of time (minutes, not seconds)
> and the server is *not* in a ckp wait state
>
> The sessions stuck on 'G', waiting for a log buffer, do nothing until
> the index build completes, then continue merrily.
>
> The log buffers are 32k default. The instance is logging to /dev/nul.
> There are 8 log files of 500 MB each.
>
> KAIO is being used, 4 cpuvps
>
> If anyone could enlighten me as to what is happening, I would
> appreciate it. A cure would be warmly received as well.
>
> tia
>
> James